1. Technical Field
The present invention relates to a projector and a method of controlling a projector.
2. Related Art
In the past, in a projector for projecting an image on a projection surface such as a screen, a distortion (a projection distortion) occurs in the projection image in the case in which the installation position of the projector fails to be the correct position with respect to the projection surface (e.g., the screen). For example, in the case in which tilted projection, in which the projection is performed with the projector tilted in a vertical direction or a horizontal direction with respect to the screen, is performed, there occurs a phenomenon (a keystone distortion) that the image displayed on the screen is distorted to have a trapezoidal shape. Therefore, as described in JP-A-9-261568 (Document 1), there has been known a projector, which forms an image distorted so as to cancel out the keystone distortion when forming the image with a light modulation device to thereby correct the projection image.
Further, as described in JP-A-2003-283963 (Document 2), there has also been disclosed a projector, which automatically detects the installation angle of the projector to perform the keystone distortion correction. According to such a projector, since the keystone distortion correction is performed in accordance with the installation angle, the trouble that the user manually performs the correction can be reduced.
In some cases, the projector is used for a demonstration in an unattended manner. In the case in which the projector is used in such a manner, the keystone distortion has occurred in the projection image in such a case that the projector has moved during the demonstration due to an unsound installation place, or that the projector has been moved by someone to thereby vary the installation angle. In such a case, by applying the configuration of the projector according to Document 2, the projection image can be corrected due to the automatic keystone distortion correction function. However, in some cases, the administrator (the user) fails to be aware of the fact that the installation angle of the projector varies when watching the projection image afterward since the projection image has been corrected by the automatic keystone distortion function. Therefore, there is a possibility that the counter measure such as readjustment of the installation place of the projector or prevention of the movement of the projector by other people is delayed.
Therefore, there has been demanded a projector capable of notifying the user of the fact that the installation angle has varied during the operation of the projector.